A testing machine is described in which a specimen contained within a water‐jacketed vessel is heated in vacuum or in a gas atmosphere by a tantalum‐tube resistance heater, and is then subjected to static tensile loads up to 100 000 psi. This machine is now in routine use at Los Alamos Scientific Laboratory for short‐time creep and stress‐rupture testing of metallic and nonmetallic specimens at 2000 to 2500°C. With minor modifications, it can also be used for longer‐period creep and stress‐rupture studies, for ordinary tensile, compressive, or shear testing, and for operation at temperatures substantially above 2500°C or down to room temperature.